took the truck to the dealer today, please note ive had the truck about 6 days now.

P0401 egr flow insufficent:

dealer cleaned TB, and EGR ports...so they say.

i replaced DPFE and they replaced the small valve forward of the DPFE

drove truck home then to work and home, just as i pull on my street CEL appears. I can only guess that its 0401 again. could the cats be clogged and causing too much backpressure and overflowing the EGR or did the dealer just blow me off? (i basicly hovered in the bay while truck got fixed, he did vaccum test and work on the truck.)

heres all my symptoms:
slightly rough idle
the random knock in pass side 3/4 area
CEL stating EGR problems


im thinking EGR valve= shot, TPS, maybe shot, the knock...jury is still out on that one.

 

Test your EGR valve yourself. It's called the suck test.

Here's WatChaDo Pheonixx -

While the truck is running @ idle, pull the hose off the EGR valve.

Plug in your own separate hose in it's place.

Suck on that hose like your drinking a milkshake while your truck is idling.

If your idle deflects or changes at all - then your EGR valve is functioning fine.

If there is NO change in idle , then your EGR valve is toast!! Insufficient.

Trust Me - This test works and will pinpoint EGR "valve" failure..

 

The 401 code takes 2 drive cycles to show again after the code is forced clear, if the fault has not been found.
They can also look at PID with a Scanner and see if the fault was found before even leaving the shop.

 

Why wouldn't they clear the damn thing then..??

Before it left the shop?


Idunno , once mine was fixed - I rebooted and it never reoccured..

 

i checked it myself with a vaccum gauge, 15 lbs and engine nearly dies. same result with the dealer. like i said I changed the DPFE, they changed the little valve in front if it. egr valve was tested and codes were reset.

went to the dealer today and got two codes...

the EGR flow insufficent thing(0401) and another one 1549, said something about intake. im guessing the intake code is being set off by the egr malfunction, no idea.

 

The 1546 code is for a v6 motor intake tuning control system.
Is the motor a v6?
Never put 15 inches of vacuum on the EGR valve. It dosent work at those levels and could damage the diaphram.
5 TO 6" max.
They need to put there scanner on and monitor the DPFE while driving, to see what it is doing in order to tell what part of the operation is faulty.
The connector or wire harness could have a problem.
Obviously the exhaust can flow from the exhaust manifold thru the restriction to the EGR valve into the intake, fine.
The fault is with the DPFE detection/operation function.
Try another DPFE and make sure the hoses are on the correct ports and not switched around.
Another test is place a tee in the EGR line between the regulator and the EGR valve and use a vacuum gauge to see if the EGR is addressed with vacuum while driving in OD and lite throttle criuse.
This tells you if the PCM is trying but the DPFE is not able to report the actions at all or within limits.
The dealer tech seems not to be trying hard enough to find the problem.
There are test methods to use on the DPFE but subbing with a known good unit is a lot easier. It eliminates the need for test equipment and test info.
You can't dance around the outside and wish for magic to happen.
Somebody has to get their 'tail' into the problem and want to find the answer.
Best I can do from remote is tell you about the system and some things to do.
Good luck.

 

at current the lines come off the EGR tubes and DO NOT cross and are in good condition. the lines crossing or not has been a issue with me as i could swear they crossed at one point. Do they cross or not cross? ill take some pics of the engine tomorrow and post them here so maybe you guys can tell me if something is connected wrong or maybe you will see somethign i missed. while im at it i may try and grab a sound clip of my "random knock" sound. this is a 4.6L V8 why am i getting a code for a V6 motor? yah i meant 5 not 15, lil typo there lol.

thanks again bluegrass